We increasingly get questions about the impact of soybean growth habit on soybean yield. Soybeans have two growth habits: Indeterminate and determinate. Indeterminate varieties will continue vegetative growth on the mainstem after the soybeans have moved into reproductive development whereas determinate varieties will cease vegetative growth on the mainstem after the plant has moved into reproductive development. Regardless of growth habit, soybeans will still flower for several weeks but generally indeterminate varieties will flower over a longer period than determinate varieties. This has driven questions about the value of the indeterminate growth habit in stressful conditions. Historically the indeterminate growth habit was only found in earlier maturing varieties (≤MG4), however now the indeterminate growth habit is available is later maturing varieties and so investigating the impact of growth habit on production within the same maturity group is needed.
Two graduate students under the direction of Dr. Dominic Reisig (Hayden Schug and Taynara Possebom) did some great work comparing soybean growth habits and investigating implications on corn earworm management. In this work comparing two pairs of varieties with different group habits, generally there were minimal differences in yield between the two soybean growth habits.
In 2023 we expanded that work to look at a broader range of MG5 varieties with the different soybean growth habits. We compared 4 MG5 varieties with the indeterminate growth habit to 4 MG5 varieties with the determinate growth habit with late April and early May planting dates.
Soybean Height: Soybean height was taller in determinate varieties at flowering than indeterminate varieties at two of the the three locations (data not shown). However, by the time that soybeans reached maturity the indeterminate varieties were taller than the determinate varieties at three of four environments (Figure 1).
